Most commercial beers are made with carefully selected strains of yeast, but brewers of lambic beers leave things up to chance. Belgian lambic beers are left in open vats where wild yeast and bacterias are allowed to take up residence. Once the fermentation process begins, the beer is stored in barrels and left to age for up to three years.
The result is a distinctly sour beer with mild carbonation, a cloudy appearance, and a thick mouthfeel. In a word, funky. Think of the difference between bread made with commercial yeast verses bread made using a sourdough starter and you'll start to get the idea.
Although it's not a requirement, many lambics are also fermented with fruits like raspberries, apricots, and even muscat grapes. This adds another layer complexity to the beer, balancing the sour brew with tart and sweet fruit flavors.
We think lambics have gotten an unfair reputation in recent years for being overly sweet and syrupy. In fact, many producers have started adding fruit syrups directly into the beer instead of fermenting with whole fruits. Some beers made this way are decent, while others justify their cloyingly sweet reputation.
It's worth doing your homework and seeking out quality lambic beers. The Beer Advocate, based in Boston, has an exhaustive list of both fruit and unblended lambics rated by the community and Eric Asimov's 2006 article from the New York Times also makes some good recommendations (links below).
We've only had the chance to try a few lambics ourselves, and we're very eager to try more. They make an excellent after-dinner beverage, particularly if paired with fruits that have been poached in the same beer!
Are you a fan of lambic beers?